Gas burner



Sept. 30, 1969 w. H. DE LANCEY 3,469,791

GAS BURNER Filed Jan. 2, 1968 INVENTORS IVA/new H. Debra/cs7 BY H585! GHa s Don-up W. Hnkrzlu Ts--as I. Ensna 5 MC n/am:

3,469,791 GAS BURNER Warren H. De Lancey, Herbert G. Hays, and Donald W.Hartzeil, Elyria, @hio, assignors to American Standard Inc, acorporation of Delaware Filed Jan. 2, 1968, Ser. No. 704,968 Int. Cl.1305b 7/00; F23d 13/24 U5. Cl. 239-4195 14 Claims ABSTRACT 033 THEDISCLOSURE The present burner comprises an inner slotted or perforatedgas distributor tube and an outer ported flame tube, the blind ends ofsaid tubes being connected together by a novel low cost cap structure.

This invention relates to gas burners, as are used for example indomestic furnaces.

The inner tube of the burner is slit or perforated for its full length,and dimples or projections of predetermined height are formed in one ofthe tubes, whereby the inner tube is allowed to spring outwardly so thatthe dimples maintain an accurate spacing between the tubes, even whenthe two tubes tend to expand non-uniformly due to thermal effectsresulting from the location of the burner ports.

To provide precise metering of the gas flow the twotube burner isconstructed so that the space between the tubes may be varied to aslight extent along he burner tube length; this gives a more uniformfire along the burner length.

A feature of the burner installation is a spring type mounting meanstrained between the burner and a fuel supply structure. This mountingmeans causes the remote end of the burner to interlock with a supportstructure, while at the same time permitting the burner to be readilyremoved for cleaning, repair or replacement. Due to its location themounting means compensates for longitudinal thermal expansion andcontraction of the burner.

An additional feature of the two-tube burner is the provision ofmultiple rows of flame ports in the outer tube and multiple rows of gassupply openings in the inner tube, whereby each row of flame ports issupplied with fuel flowing circumferentially from two directions in thespace between the two tubes. This feature enables higher heat outputs tobe achieved without resorting to larger tube diameters; additionally theuse of multiple rows of flame ports may give better distribution of theflame pattern in relation to the heated surface area of the heatexchanger with which the burner is used (less likelihood of hot spots).

THE DRAWINGS FIG. 1 is a top plan view of a burner installationembodying the invention.

FIG. 2 is a sectional view taken on line 22 in FIG. 1.

FIG. 3 is a sectional view taken on line 3-3 in FIG. 2.

FIG. 4 is a transverse sectional view taken on line 4-4 in FIG. 2.

FIG. 5 is a sectional view taken in the same direction as FIG. 4, butthrough a variation of the invention.

FIG. 6 is a fragmentary sectional view illustrating an additionalembodiment of the invention.

GENERAL ARRANGEMENT The burner, designated 18, comprises an innercylindrical tube 2!; and an outer cylindrical tube 22. Fuel gas enterstube 2% in the arrow 16 direction, and flows longitudinally within thetube toward end closure 34; primary air is entrained with the gas as itissues from the spud. A full length slot 26 in the lower surface of tube20 directs "ice the mixture into the annular space 21 so that it flowsupwardly around the tube 20 outer surface before reaching the flameports 30 and 32 in the upper wall portions of tube 22.

Ignition of the burner may be accomplished by a flamecarrying hoodstructure 60 attached to the front or rear end of the burner; thedrawing illustrates a rear end location. The hood structure receives itsgas supply from the burner interior via passages 74 and 76, and a pilotflame (not shown) ignites the gas as it issues from a slot 82 in thehood structure.

In usual practice a number of the illustrated burners, each having ahood structure 60, are positioned side-byside to receive fuel gas from acommon manifold 10. Each hood structure 60 transmits flame to its burnerand to the hood structure on the next adjacent burner. In this way anumber of burners are effectively lighted from a single pilot flame.

FUEL GAS SUPPLY There is shown a burner installation comprising a fuelgas manifold pipe 10 of general circular cross section. At spaced pointsalong its length the manifold pipe is provided with bosses 12 whichfixedly receive the fuel gas spuds 14, only one of which is shown in thedrawings. The raw fuel gas flows longitudinally through manifold pipe10, and thence turns into the individual spuds 14 into the burner itentrains primary air from the surrounding area.

BURNER PER SE Axially aligned with each spud 14 is an elongated tubulargas burner 18 comprising an inner cylindrical metal tube 20, and anouter cylindrical metal tube 22. The lengths and diameters of the tubescan vary, but illustratively the tubes can be about twenty inches long,the inner tube can have a diameter of about one inch, and the outer tubecan have a diameter of about one and one quarter inches; the tubediameters can of course vary in an absolute sense, but there is anappropriate ratio between the tube diameters for a pressure drop featurewhich will become apparent hereinafter. The tubes are in practice muchlonger in relation to their diameters than would appear from thedrawings. To clarify this, FIGS. 1 thru 3 are shown with breaksintermediate the ends of the tubes.

Inner tube 20 is formed from a sheet of steel which preferably has somespringiness in it so that when it is formed into the cylindricalconfiguration it will tend to spring outwardly toward the surface oftube 22. This spring-out characteristic is made possible by correctchoice of material and by forming a break or slit along the entirelength of the tube. In FIG. 3 this break line is denoted by numeral 24;it includes an elongated slot or aperture 26 extending substantially thelength of the tube, but terminating a short distance from the open tubeend as shown in FIGS. 2 and 3. Slot 26 could if desired extendrearwardly to the tube end, thus eliminating the rearmost break line 24.Alternately the single aperture 26 could be replaced by a series ofapertures separated by individual breaks or slits.

To keep the inner tube 20 accurately spaced from outer tube 22 the innertube is preformed with outwardly projecting dimples 28; alternately someor all of the dimples could be formed as inward projections from tube22. As shown in FIG. 4 there are a suitable number of dimples spacedcircumferentially around the tube 20 and contacting the inner surface oftube 22. FIG. 4 is taken through one plane only of the tube, and inpractice additional sets of dimples are provided at other longitudinallocations along the inner tube. Thus, with a twenty inch length tubethere might be provided five sets of dimples spaced evenly along thetube length. These dimples cooperate with the spring-out nature of theinner tube to accurately space the outer surface of the inner tube fromthe inner surface of the outer tube.

Outer tube 22 is continuous about its circumference, but may in practicebe formed with a seam (not shown) along its entire length. The tube maythus be formed from flat sheet metal, and at the same time stamped withtwo rows of flame ports and 32, as well as certain other openings, to bedescribed hereinafter. The flame ports preferably extend substantiallythe entire length of tube 22 except for the tube end portions.

As shown best in FIG. 2, the two tubes 20 and 22 are connected at theirright ends by a one-piece unitary cap structure 34 which has threediiferent diameters, indicated by numerals 36, 38 and 40. Cap portion 38snugly telescopes within tube 22, and cap portion 40 snugly telescopeswithin tube 20, thus connecting the tube ends together and sealing thejoint therebetween; the cap is preferably welded or staked to tube 22but not to tube 20. The left ends of the burner tubes 20 and 22 areconnected and sealed by forming the inner tube so that its end portionflares outwardly, as at 48. The flared portion thus fits snugly butremovably within tube 22 to act as a seal and as a support.

BURNER MOUNTING Exposed portion 36 of cap 34 may be provided with slots42 and 44 (FIG. 3) for insertion onto an angle iron-type supportstructure 46 which is a fixed part of the burner installation. Capstructure 34 thus performs a triple function, namely as a connectionbetween tubes 20 and 22, as a sealing means between the two tubes; andas a mounting means for the rear end of the burner.

The front or left end of the burner may be mounted on the fuel gas spud14 by means of a flat metal bow spring 50, whose mid-portion is providedwith a circular opening formed by flanging the spring material axially,as at 52. The opposite ends of the bow spring are turned or deformedoutwardly as at 54 to form. detents which snap into rectangular openings56 formed in the wall of tube 22. The detents 54 project through slots57 in the left edge of tube 20, but the retention shoulder for eachdetent is preferably formed by the opening 56 in tube 22.

Preferably the bow spring is preformed with its ends spaced furtherapart than shown in FIG. 2. The bow spring thus tends to have itsdetents 54 lock into openings 56 when the spring is hand-installed. Theinner tube 20 must of course be assembled into tube 22 with its slot 26remote from ports 30 and 32; otherwise the annular space 21 will notserve its desired gas control function. To assure correct factoryassembly the bow spring 50 is formed with one detent 54 wider than theother; also the different openings 56 and different slots 57 are ofdifferent widths. For example the upper detent 54, upper opening 56 andupper slot 57 (FIG. 1) are narrower than the lower detent 54, loweropening 56 and lower slot 57 (FIG. 3). This insures that tube 20 willnot be installed in a position rotated 180 degrees from that shown inFIG. 2.

Preferably burner 18 is supported entirely by the gas supply manifold 10and support structure 46. Thus, spring 50 transmits the weight of thelefthand portion of the burner onto spud 14, and no additional supportmechanism is used. It will be noted that spring 50 occupies free spacebetween burner 18 and fuel supply manifold 10, i.e., the spring is thesole device between the manifold and the burner. This arrangementenables burner 18 to be manually withdrawn away from structure 46 in thearrow 19 direction, thus removing slots 42 and 44 from structure 46 andincidentally compressing spring 50. The burner can obviously then bemanipulated by an upward and rightward motion to remove theburner-spring assembly from the fixed gas manifold structure.

4 BURNER DISMANTLING Preferably the burner per se is formed so thatinner tube 20 can be separated from outer tube 22 for cleaning, repairor replacement. Toward this end cap 34 is constructed as a snug lit intube 20; no welding, soldering, etc., is used. Cap 34 is howeverpreferably welded or otherwise permanently secured to tube 22 topreserve structural unity to the burner. Spring 59 can be dissociatedfrom the burner by inward pressure on its U- shaped portions 51 incidentto on-the-job removal of tube 20.

After removal of spring 50 the inner tube 20 can be removed from outertube 22- by inserting a nail or similar pinlike element (not shown)through two radially aligned openings 53 in tube 20. Tube 22 is providedwith slots 55 in its end edges which register with openings 53 to permitthe pin-like element to be drawn leftwardly while tube 22 is held in astationary position. The pinlike element may thus be used to draw tube20 out of tube 22.

FLAME CARRY-OVER HOOD STRUCTURE In furnace installation a number ofburners 18 would be arranged between manifold 10 and support structure46. Normally, all of these burners would be ignited from a single pilotflame located adjacent one of the burners. To carry the flame from thepilot to the adjacent burner and from burner to burner, each burner isequipped with a hood structure 60 formed in the present instance by asingle sheet of metal having two wall portions 62 and 64 doubled backonto one another in pancake fashion. As shown in FIG. 2, the lower wallportion 62 and upper wall portion 64 are joined by two connectorsections 66, which could be a single elongated section if desired.Sections 66 are not hinges but are merely temporary connectors duringassembly operations; two wall portions 62 and 64 are permanently securedtogether by spot welds 68.

Wall portion 62 is downwardly bulged-out in the area circumscribed byline 70, while wall portion 64 is bulged upwardly in the areacircumscribed by line 72, the two bulged-out areas thus forming acentral gas plenum chamber 73 for receiving a supply of gas from theburner on which the hood structure is mounted. Although not clearlyshown in the drawing, the lower surface of the bulged-out portion 70 isconcaved to conform with the surface contour of burner tube 22, thuspermitting the hood structure to be welded on and sealed to the burnertube.

Fuel gas is supplied to the hood structure plenum chamber through asmall port '74 in tube 29, and a passageway formed by two registeringopenings 76 in burner tube 22 and hood wall 62. The peripheral wallareas of the hood structure rightwardly of the plenum chamber arefacially engaged to form a seal, but the peripheral wall areasleftwardly of the lines designated by numerals 78 and 80 are spacedapart to form a slot-like passage 82. This slot-like passage has anappreciable length in the arrow 84 direction, which causes it to act asa restrictor for preventing flashback of the flame into the plenumchamber. Preferably the hood structure extends crosswise of the burnertube as shown in FIG. 1 so that portions of the slot-like passage 82 arenear the port structure for the next adjacent burner. Passage 82 thuspropagates a flame not only along the burner ports 30 and 32, but alsoonto the hood structure for the next burner in the series.

GENERAL MANNER OF IGNITION The fuel gas issuing from spud 14 entrains aquantity of primary air from the surrounding space, and the fuelairmixture is propelled by the manifold pressure into tube 20. The rush ofgas is predominantly axial, and a major part of the gas flow piles upagainst the inner surface of cap 34, where it then flows upwardlythrough passages 74 and 76 into hood structure 60. Assuming a pilotflame at the outer surface of slot 82, there will be ignition at thehood structure, and propagation of flame rightwardly along the ports 30and 32; thus the rightmost ports 30 and 32 will ignite first and theleftmost ports will ignite last. Gas mixtures which have predominantlyfilled the tube 20 are forced downwardly through the slot-like aperture26 extending substantially the full length of tube 20. The mixtures thenflow upwardly around the outer surface of tube 20 in the annular space21 before reaching the main flame ports 30 and 32.

The location of the hood structure at the rear of the burner isbeneficial in promoting quick ignition with lessened puff. This isbelieved due to the fact that the gas flows from the right closed end oftube 20 directly into the hood structure without having to build up areturn or reverse velocity pressure as may be the case when the hoodstructure is located at the entrance end of the burner.

GAS METERING Preferably the cross section of the passage formed by space21 is somewhat less than the total cross section of the flame ports 30and 32 or of the supply aperture 26. Thus, the flame ports may be tworows of circular holes inch in diameter, spaced on inch centers; theslot 26 may have a width of about 7 inch; and the annular space 21 mayhave a radial dimension of only about .06 inch. With this arrangementthe restriction in the gas passage system is supplied by passage 21.This passage is of appreciable circumferential extent or length. It thuspro vides a restriction or metering means, which causes the pressurewithin tube 20 to be greater than the pressure at the ports 30 and 32.Because of this pressure relationship there is little possibility offlame flashback into the burner. Also, experiments show that the burnerproduces a desirably short, hard, blue fire symptomatic of good airfuelmixing and distribution. In the illustrated burner the cross section ofpassage 21 is accurately maintained by the aforementioned spring-outnature of tube 20, the full length break 24 and the controlled-heightdimples 28.

In elongated burners of the illustrated type the motion of the gas intube 20 is to a large extent axial in nature, which tends to cause moregas to be delivered to the rightmost or rear ports than is delivered tothe leftmost or front ports. To minimize this tendency the annularpassage 21 is maybe slightly tapered from left to right. Thus, theleftmost dimples 28 might have a height of about .0625 inch, the nextset of dimples might have a height of about .0575 inch, and so on, withthe rightmost dimples being about .0475 inch. This taper is not largebut is sufficient to provide a substantially uniform flame height alongthe burner. We have found that the controlled height dimples will inpractice all engage the surface of the outer tube even though they areof varying height; thus, they will provide the desired spacing betweentubes.

During burner operation the upper surface areas of tube 22 will be athigher temperatures than the lower surface areas of tube 22 or tube 20because the flame heat is concentrated on the top side of tube 22. Theremay thus be some thermal distortion of the outer tube. With very longburner tubes there might be some undesirable stress build-up or changein passage 21 dimension. However the dimples 28, together with the splitnature of tube 20, allows the inner tube to follow or distort with theouter tube so that the annular passage 21 maintains its design dimensionirrespective of tube Warpage.

FIG. 5 VARIATION FIG. 5 is taken through a burner which is similar tothe FIG. 1 burner. Thus, the FIG. 5 burner utilizes an outer tube 22::and an inner tube 20a spaced apart by dimples similar to dimples 28; thedimples are not shown in FIG. 5.

In the FIG. 5 burner inner tube 20a is split, as at 24a, for its fulllength, to provide the spring-out characteristic previously mentioned.However, instead of a single gas discharge slot 26 the tube 20a isprovided with three gas discharge slots 26a, 26b and 260. The purpose inusing three slots instead of a single slot is to increase the amount ofgas supplied to the annular space 21, for thus increasing the capacityof the burner and its heat output without resorting to a larger tubediameter.

The ports 30 and 32 may have greater diameters than the correspondingports in the FIG. 4 embodiment; additionally the FIG. 5 ports 30 and 32may be spaced somewhat further apart. As shown in FIG. 5 port 32 is atabout the 2 oclock position, openings 26a are at about the 5 oclockposition, openings 26b are at about the 7 oclock position, ports 30 areat about the 10 oclock position, and openings 26c are at about the 12oclock position. Opening 26c supplies gas to both ports 30 and 32,opening 26a supplies gas primarily only to port 32, and opening 26!;supplies gas primarily only to port 30. The arrangement of openings andports is such that each port 30 or 32 is supplied with gas flowing inspace 21 from two directions. In this way different sections of space 21perform as metering passages while still achieving a high flow ratethrough each flame port 30 and 32. The capacity and heat output of theburner is thus increased without flame nonuniformities.

FIG. 6 VARIATION In the FIG. 6 burner the flame carry-over hoodstructure 60 is positioned adjacent the entrance end of the tubeassembly, rather than near the downstream end as in FIG. 2; the actualhood construction may however be the same in each case. The reason forrelocation the hood in FIG. 6 is that in certain burner installationsthe entrance end of the tube assembly is the only place available toreceive the hood or to make the hood accessible for automatic or manuallighting purposes.

Preferably the inner tube 20 in FIG. 6 is provided with a struck-downtab which has the function of deflecting a portion of the oncoming gastoward openings 76 for thus accomplishing rapid flame propagation. Thetab therefore minimizes the aforementioned problems of ignition puff andreverse velocity mentioned earlier herein. The tab dimensions may bevaried, but as an example, when the inner tube 20 has a diameter ofabout one inch tab 90 may have a length of about one inch and a width ofabout one quarter inch; the formed slot 92 would of course necessarilyhave the same dimensions as the tab.

FIG. 6 illustrates an alternate method of mounting the burner tubeassembly shown in FIG. 2. In FIG. 6 each tube assembly has its entranceend area resting in a semicircular notch or seat formed in theupstanding leg of a transversely extending angle iron 94. To hold thetube assembly down on the angle iron there is provided a metal strip 96having a turned-out upper end portion 98 extending through a slot intube 22; a screw 99 threads into an opening in angle iron 94 to retainstrip 96 in place.

Although not shown in FIG. 6, the rear end portion of the tube assemblymay be supported on an angle iron 46 similar to that shown in FIGS. 2and 3. The spacing be tween angle irons 46 and 94 would in practice varysomewhat from design value, and accordingly the slot position, etc., ischosen so that under perfect circumstances the strip 96 is angled ortilted as shown. This allows the screw 99 to screw down tight againststrip 96 and take up any play or looseness.

It is claimed:

1. A gas burner comprising an inner elongated gas supply tube having gasdischarge aperture means extending therealong, and an outer elongatedburner tube having flame port means extending therealong; said gassupply tube having an entrance opening at one end thereof for admittingfuel-air mixtures to the supply tube interior; the two tubes beingsubstantially coextensive in length, and the diameters of the tubesbeing such as to provide an annular space between the outer surface ofthe inner tube and the inner surface of the outer tube; the ends of thetubes remote from the entrance opening being closed whereby fuel-airmixtures are caused to travel longitudinally within the inner tube,through the discharge apertures, and into the space between the tubesbefore reaching the flame ports; closure of the remote ends of the tubesbeing effected by a sealing means which comprises a single unitary caphaving a first large diameter portion closing the end of the outer tube,and a second small diameter portion closing the end of the inner tube.

2. The gas burner of claim 1 wherein the cap is a onepiece element.

3. The gas burner of claim 1 wherein said cap is provided with anexposed tubular end portion having slots therein for mounting one end ofthe burner on a fixed support structure.

4. The gas burner of claim 1 wherein the entrance end of the inner tubeis outwardly flared to snugly telescope within the outer tube, wherebythe tubes are connected at one end by the flared tube portion and at theother end by the unitary cap.

5. A gas burner comprising an outer elongated burner tube having flameports extending therealong, and an inner elongated gas supply tubehaving at least one gas discharge aperture extending therealong; meanssealing the tubes together at one end thereof; said one end of the innertube being open to admit fuel-air mixtures to the burner, theaforementioned sealing means causing the mixtures to travellongitudinally within the inner tube and to then pass through thedischarge aperture into the space between the tubes; a second sealingmeans closing the other end of the tubes; and means for accuratelyspacing the inner tube from the outer tube, said spacing meanscomprising a slit formed substantially along the entire length of theinner tube, whereby said inner tube is enabled to spring outwardlytoward the outer tube along its entire length, and dimples formed atspaced points along at least one of the tubes, said dimples projectingfrom said one tube toward the other tube to engage same and therebydetermine the spacing between the tubes.

6. The burner of claim 5 wherein the gas discharge aperture in the innertube is formed by a single elongated slot extending along the inner tubefor a distance corresponding generally to the portion of the outer tubewhich is equipped with flame ports.

7. The burner of claim 5 wherein the flame ports in the outer tube arecircumferentially spaced from the gas supply apertures in the innertube, whereby gas leaving the supply aperture is required to traverse asubstantial portion of the inner tube circumference before reaching theburner ports.

'8. The burner of claim 5 wherein the total flame port area is greaterthan the total passage cross section provided by the space between theinner and outer tubes, whereby said space constitutes a passagerestriction tending to prevent flashback into the burner.

9. The burner of claim 5 wherein the dimples are of graduated height,the dimples adjacent the closed end of the tube being shorter than thoseadjacent the open end of the tube whereby a tapered passage space isformed between the two tubes.

10. A gas burner comprising an outer tube having burner ports extendingtherealong, and an inner tube having at least one gas supply apertureextending therealong; said inner tube having a main portion spaced fromthe outer tube to provide a circumferential gas passage between thetubes, means for admitting fuel and air mixtures to the burner via oneend of the inner tube; the burner ports comprising a first set of portsextending along the outer tube at approximately the 2 oclock positionand a second port means extending longitudinally along the outer tube atabout the 10 oclock position; the apertures in the gas supply tubecomprising first aperture means extending longitudinally along the tubebetween the 10 oclock and 2 oclock positions, and a second aperturemeans extending longitudinally along the inner tube between the 2 oclockand 10 oclock positions.

11. The burner of claim 10 wherein the second aperture means comprisestwo sets of apertures, one set located at about the 5 oclock position,and the other set located at about the 7 oclock position.

12. A gas burner installation comprising a fuel supply structure and asupport structure spaced therefrom; an elongated fuel gas burner havingone end thereof interlocked with the support structure; and spring meansdetachably connected between the fuel supply structure and the other endof the burner; said spring means occupying space between the burner andfuel supply structure to permit the burner to be detached from thesupport structure by movement thereof toward the fuel supply structure.

1'3. The burner of claim 12 wherein the spring means comprises a bowspring having its mid-point connected with the fuel supply structure andits ends connected with the burner tube, said ends including outwardlyprojecting detents arranged to snap into retention openings in theburner.

14. The installation of claim 12 wherein the burner comprises an innergas supply tube and an outer burner tube, one of said tubes havingopenings and the other tube having slots extending from one of its endedges for registry with said openings, whereby a tool can be insertedthrough the openings to withdraw the inner tube from the outer tube.

References Cited UNITED STATES PATENTS 3,156,292 11/1964 Ross 239419.53,198,238 8/1965 Hughes 239417.5 3,259,170 7/1966 Koehrer 239-41753,314,610 4/1967 Reznor 239417.5

EVERETT W. KIRBY, Primary Examiner US. Cl. X.R.

